Firefox - CPU usage at full power

[mastablasta]

I know the system is less than ideal, however this worked well in the past and it still works nicely on windows PC. i would get high usage on both cores there only in the first 10 or20 minutes as the antimalware runs. but after that it is quite calm.

here i get 100% usage with one or two tabs open. the Radeon drivers seem to be working ok (as far as HW acceleration is concerned. tried to play a few old games and they work OK. of course more work on the win7 starter which is on the other side of the hard disk.

occasionally i noticed the fans would get loud and sometimes the desktop would freeze. so i guess i should monitor the temperature as well. but in my opinion there is no good reason to get the CPU working so hard just to display a page. does this have something to do with flash? 14.04 had fglrx drivers and i haven't noticed high battery use there or high CPU usage,

attached is the CPU fluctuation as i was reading The Guardian website on one tab. here is the PC data:

System:    Host: gregor-prenosnik Kernel: 5.3.0-40-generic x86_64 bits: 64 Desktop: KDE Plasma 5.12.9
         Distro: Ubuntu 18.04.4 LTS
Machine:   Device: laptop System: Hewlett-Packard product: HP Pavilion dm1 Notebook PC v: 0699100000204600000300100 serial: N/A
         Mobo: Hewlett-Packard model: 3387 v: 36.18 serial: N/A BIOS: Hewlett-Packard v: F.17 date: 10/29/2012
Battery    BAT0: charge: 37.7 Wh 77.9% condition: 48.4/48.4 Wh (100%)
CPU:       Dual core AMD E-450 APU with Radeon HD Graphics (-MCP-) cache: 512 KB
         clock speeds: max: 1650 MHz 1: 1158 MHz 2: 1646 MHz
Graphics:  Card: Advanced Micro Devices [AMD/ATI] Wrestler [Radeon HD 6320]
         Display Server: x11 (X.Org 1.20.5 ) drivers: ati,radeon (unloaded: modesetting,fbdev,vesa)
         Resolution: 1366x768@60.02hz
         OpenGL: renderer: AMD PALM (DRM 2.50.0 / 5.3.0-40-generic, LLVM 9.0.0) version: 3.3 Mesa 19.2.8
Audio:     Card-1 Advanced Micro Devices [AMD/ATI] Wrestler HDMI Audio driver: snd_hda_intel
         Card-2 Advanced Micro Devices [AMD/ATI] SBx00 Azalia (Intel HDA) driver: snd_hda_intel
         Sound: Advanced Linux Sound Architecture v: k5.3.0-40-generic
Network:   Card-1: Qualcomm Atheros AR9485 Wireless Network Adapter driver: ath9k
         IF: wlo1 state: up mac: 
         Card-2: Realtek RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller driver: r8169
         IF: eno1 state: down mac: 
         Card-3: Atheros
         IF: null-if-id state: N/A speed: N/A duplex: N/A mac: N/A
Drives:    HDD Total Size: 500.1GB (6.0% used)
         ID-1: /dev/sda model: Hitachi_HTS54755 size: 500.1GB
Partition: ID-1: / size: 141G used: 24G (18%) fs: ext4 dev: /dev/sda6
         ID-2: swap-1 size: 4.27GB used: 0.11GB (3%) fs: swap dev: /dev/sda7
RAID:      No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors:   System Temperatures: cpu: 67.5C mobo: N/A gpu: 67.0
         Fan Speeds (in rpm): cpu: N/A
Info:      Processes: 160 Uptime: 8 min Memory: 1137.6/1586.8MB Client: Shell (bash) inxi: 2.3.56

btw Kubuntu forums one tab open keeps CPU at 6-10% which is kind of expected value. even 20 would be ok but 100%?!?!